Browsing by Author "Schenck, W.S."
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Item Basic Data For The Geologic Map Of The Seaford Area, Delaware(Newark, DE: Delaware Geological Survey, University of Delaware, 1995) Andres, A.S.; Ramsey, K.W.; Schenck, W.S.The Seaford area geologic mapping project (Andres and Ramsey, 1995) was conducted by Delaware Geological Survey (DGS) staff and focused on the Seaford East (SEE) and Delaware portion of the Seaford West (SEW) quadrangles (Fig. 1). Data evaluated in support of mapping from these quadrangles and surrounding areas are documented in this report.Item Bedrock Geologic Map of the Delaware Piedmont(Newark, DE: Delaware Geological Survey, University of Delaware, 2021-06) Schenck, W.S.The Piedmont rock units in Delaware, and bedrock geologic map of Schenck et al. (2000) are revised in this report based on new rock geochemistry, geochronometric data, petrography, and recent detailed mapping. Major revisions include: • revising the extent of the Christianstead Gneiss and Windy Hills Gneiss • abandoning the Wissahickon Formation as originally mapped in Delaware by Bascom (1902, 1905) and Bascom et al. (1909, 1920, and 1932) and replacing it with the Mt. Cuba Gneiss, a lithodeme of the West Grove Metamorphic Suite (Bosbyshell et al., 2012, 2013, 2014, 2015), and reserving the Wissahickon Schist/Formation for the metasediments on the east side of the Wilmington Complex magmatic arc and referring to them herein as Wissahickon Formation (restricted sense) • extending the Rosemont Shear Zone from Pennsylvania southwest through Delaware to Maryland separating the Mt. Cuba Gneiss and the Wilmington Complex • formally naming and describing two new units in the Wilmington Complex - the Greenville Gabbro and the Thompsons Bridge Gneiss. Additional Notes Plate 1 of OFR54 can also be viewed in a Web Mapping Application. Layers can be turned on and off and manipulated under the "Layers" icon in the upper right hand corner. Cross section is available by clicking on the cross section line. Rock unit descriptions available by clicking on the geologic map. OFR54 Plate 1 (Bedrock Geologic Map of the Delaware Piedmont) Web Mapping Application Plate 1 Summary The vector data set contains the rock unit polygons for the surficial geology for DGS Open File Report 54 - Plate 1. The Piedmont rock units in Delaware, and bedrock geologic map of Schenck et al. (2000) are revised on this map based on new rock geochemistry, geochronometric data, petrography, and recent detailed mapping. Major revisions include: • revising the extent of the Christianstead Gneiss and Windy Hills Gneiss • abandoning the Wissahickon Formation as originally mapped in Delaware by Bascom (1902, 1905) and Bascom et al. (1909, 1920, and 1932) and replacing it with the Mt. Cuba Gneiss, a lithodeme of the West Grove Metamorphic Suite (Bosbyshell et al., 2012, 2013, 2014, 2015), and reserving the Wissahickon Schist/Formation for the metasediments on the east side of the Wilmington Complex magmatic arc and referring to them herein as Wissahickon Formation (restricted sense) • extending the Rosemont Shear Zone from Pennsylvania southwest through Delaware to Maryland separating the Mt. Cuba Gneiss and the Wilmington Complex • formally naming and describing two new units in the Wilmington Complex - the Greenville Gabbro and the Thompsons Bridge Gneiss.Item Bedrock Geologic Map Of The Piedmont OF Delaware And The Adjacent Pennsylvania(Newark, DE: Delaware Geological Survey, University of Delaware, 2000) Schenck, W.S.; Plank, M.O.; Srogi, L.A.Item Bedrock Geology Of The Piedmont Of Delaware And Adjacent Pennsylvania(Newark, DE: Delaware Geological Survey, University of Delaware, 2000) Plank, M.O.; Schenck, W.S.; Srogi, L.A.This report accompanies a new map that revises the original bedrock geologic maps of the Delaware Piedmont compiled by Woodruff and Thompson and published by the Delaware Geological Survey (DGS) in 1972 and 1975. Combined detailed mapping, petrography, geochemistry, and U-Pb geochronology have allowed us to redefine two rock units and formally recognize eleven new units. A section of the Pennsylvania Piedmont is included on the new map to show the entire extent of the Mill Creek Nappe and the Arden Plutonic Supersuite.Item Data Report On Rock Cores From Red Mill Road, Harmony Road, Prices Corner, And Newport, Delaware(Newark, DE: Delaware Geological Survey, University of Delaware, 1995-06) Schenck, W.S.; Plank, M.O.The Delaware Piedmont is underlain by metamorphosed sedimentary and igneous rocks of Middle Proterozoic to Paleozoic age. The rocks have been studied for many years, but because of poor exposure, high-grade metamorphism, and intense deformation, it has been difficult to identify units, understand their stratigraphic relationships to one another, and determine their origin and history; however, northern Delaware occupies a critical position in the central Appalachian Piedmont, and understanding its geology is key to understanding the geology of this region.Item Delaware Geological Survey Petrographic Data Viewer(Newark, DE: Delaware Geological Survey, University of Delaware, 2021-05) Schenck, W.S.; Wang, L.T.Petrography is a branch of geoscience focused on the description and classification of rocks, primarily by microscopic study of optical properties of minerals. A thin sliver of rock is cut from a sample, mounted on a glass slide, ground to approximately 30 microns (0.03mm), and viewed under a microscope that uses polarized light. By observing the colors produced as plain polarized light and crossed (90 degrees) polarized light shines through the minerals, petrologists can determine the minerals that comprise the sampled rock. The data and photomicrographs of thin sections within the Delaware Geological Survey (DGS) Petrographic Data Viewer represent the total collection of the Delaware Geological Survey for the Delaware Piedmont and surrounding areas. The data viewer includes slides from DGS research, slides donated by researchers, and slides culled from class reports, master's theses, and Ph.D. dissertations. Within the application, the “Slide Made For” field identifies the original owner of the thin section. The researchers include: John Branca, A.D. Cohen, Bernard Dirska, Gregory S. Ghon, G. Michael Hager, C. Scott Howard, Guy W. Metz, Margaret O. Plank, LeAnn Srogi, Richard F. Ward, and DGS. Existing data/slide descriptions have been included; however, no attempt was made to change the data/descriptions originally prepared by these researchers other than to correct typographical errors. These data appear as they were originally presented unless noted that modifications were made at a later date. Additional Notes The zoom tool allows one to focus on an area of interest. Click on an outcrop (sample) location to open a popup window containing the data for the selected sample(s). The popup window also includes thumbnail photomicrographs of the thin section in both plain polarized light and crossed polarized light. Click the thumbnail to open a full-size image. If interested in specific outcrops or thin sections, use the search tool to query by DGS outcrop ID, lithology, or address. Launch the Delaware Geological Survey Petrographic Data Viewer References Branca, J., 1979, Petrology and structure of the Glenarm Series and associated rocks in the Mill Creek area, Delaware: Newark, Delaware, University of Delaware, unpublished Master's thesis, 84 p. Cohen, A. D., 1964, Petrologic analysis of the gneisses at Windy Hills Bridge, Delaware: Newark, Delaware, University of Delaware, unpublished Geo402 class paper, DGS Sample/thin section record only. Dirska, B., 1990, Petrology and evolution of the plutonic igneous rocks of the Wilmington Complex, northeastern northeastern Delaware and southeastern Pennsylvania: Newark, Delaware, University of Delaware, unpublished Master's thesis, 227 p. Gohn, G.S., John, C.J., Hager, G.M., Niemann, N.L., Grundl, T.J., Bair, P.L., Dempsey, J.M., Ferris, L.A., and Lazzeri, J.J., 1974, Reconnaissance geology of the Mill Creek uplift, northeastern Delaware and southeastern Pennsylvania Piedmont: Newark, Delaware, University of Delaware, unpublished report, 23 p. Hager, G. M., 1976, Petrologic and structural relations of the crystalline rocks in the Hoopes Reservoir area, Delaware: Newark, Delaware, University of Delaware, unpublished Master's thesis, 79 p. Howard, C. S., 1984, Geological and geophysical investigations in the Wilmington Complex/Wissahickon Formation boundary area, Delaware Piedmont: Newark, Delaware, University of Delaware, unpublished Master's thesis, 258 p. Metz, G. W., 1988, The petrology of the cordierite-bearing gneisses near Montchanin, Delaware: Newark, Delaware, University of Delaware, unpublished senior thesis, 44 p. Plank, M. O., 1989,Metamorphism in the Wissahickon Formation of Delaware and adjacent areas of Maryland and Pennsylvania: Newark, Delaware, University of Delaware, unpublished Master's thesis, 111 p. Srogi, L., 1988, The petrogenesis of the igneous and metamorphic rocks in the Wilmington Complex, Pennsylvania-Delaware Piedmont: Philadelphia, Pennsylvania, University of Pennsylvania, unpublished Ph. D. dissertation, 613 p. Ward, R. F., 1958, Petrology and metamorphism of the Wilmington Complex Delaware adjacent Pennsylvania and Maryland: Philadelphia, Pennsylvania, Bryn Mawr College, unpublished Ph. D. dissertation, 103 p.Item Delaware Piedmont Geology(Newark, DE: Delaware Geological Survey, University of Delaware, 1998) Plank, M.O.; Schenck, W.S.The Red Clay Creek Valley traverses geologic features that have long been recognized as important to science, industry, and history. The reader will note that within the text “Piedmont,” and “Atlantic Coastal Plain” are capitalized. This is because these are formal geologic provinces. The “Fall Line” or “fall zone” is also an important geologic area. The Fall Line is the contact where the hard crystalline rocks of the Piedmont dip under and disappear beneath the sediments of the Coastal Plain. The fall zone is a narrow zone that parallels the Fall Line where rapids and waterfalls are common. The landscape and rock types shown in northern Delaware are classical examples of the larger geologic features that dominate the geology of eastern North America.Item Delaware's State Boundaries(Newark, DE: Delaware Geological Survey, University of Delaware, 1989-06) Schenck, W.S.One hundred seventy-nine monuments help to mark Delaware's boundaries with Maryland, Pennsylvania, and New Jersey. Although there are only four major boundaries, there are seven boundary lines that make up the confines of the State. They are the east-west boundary, or Transpeninsular Line; the north-south boundary, or the Tangent Line, Arc, and North lines; the Delaware-Pennsylvania boundary, including the Top of the Wedge Line and the 12-mile Circle; and the Delaware-New Jersey boundary including the 1934 Mean Low Water Line and the Delaware Bay Line. Only the Transpeninsular, Tangent, Arc, North, 12-mile Circle, and 1934 Mean Low Water lines are monumented. The Delaware Bay Line is defined by the navigational channel. The boundaries described here evolved through long, complex histories (see references). They are based largely on adjudication in England of conflicting claims by the Penns and the Calverts for the Pennsylvania and Maryland colonies.Item Geochemistry Of The Mafic Rocks, Delaware Piedmont And Adjacent Pennsylvania And Maryland: Confirmation Of Arc Affinity(Newark, DE: Delaware Geological Survey, University of Delaware, 2001) Plank, M.O.; Srogi, L.A.; Schenck, W.S.; Plank, T.A.Geochemical data from Ordovician and Silurian mafic rocks in the Wilmington Complex in Delaware, the James Run Formation in Cecil County, Maryland, and the Wissahickon Formation in Delaware and Pennsylvania were collected in conjunction with preparation of a new geologic map of the Delaware-Pennsylvania Piedmont. Although concentrations of most elements may have been disrupted by metamorphism, the more stable high field strength elements, including the rare earth elements (REE), are consistent within mapped lithodemic units and are compared to modern basaltic magmas from relatively well known tectonomagmatic environments.Item Geologic Map Of Southern Delaware(Newark, DE: Delaware Geological Survey, University of Delaware, 1990-06) Ramsey, K.W.; Schenck, W.S.This geologic map shows: (1) distribution of geologic units found at the land surface; (2) updip limit (generally the northern extent) of Miocene and Pliocene geologic units found in the subsurface; and (3) locations of major subsurface faults that affected deposition of the Miocene and Pliocene geologic units. The geologic units shown are defined on their dominant lithologies (i.e., sand, silt, clay) and other characteristics such as presence or absence of shells or other fossils and range of colors.Item A Guide To Information On Benchmarks In Delaware(Newark, DE: Delaware Geological Survey, University of Delaware, 1982-03) Schenck, W.S.To conduct an elevation survey, a surveyor needs a starting point for which the exact elevation above mean sea level is known. These starting points are called benchmarks. State and federal agencies install benchmarks throughout every State, creating a network of elevation points which covers the entire continental United States. These benchmarks are considered to be permanent, and usually consist of a brass, bronze, or aluminum disc about 4 inches in diameter mounted in a cement post or in a drill hole in a permanent foundation. Each benchmark also has the installing agency's name and an identification number stamped into it. In December of 1980 the Federal Emergency Management Agency (FEMA) allotted the State of Delaware funds to determine the number and condition of federal benchmarks and other elevation reference control points. The National Flood Insurance Program (NFIP), contained within FEMA, requires accurate flood surveys of property in flood-prone areas. An extensive and accurate benchmark network throughout the State is needed to help meet these needs.Item Physiographic Regions of the Delaware Atlantic Coast(Newark, DE: Delaware Geological Survey, University of Delaware, 2000) Ramsey, K.W.; Schenck, W.S.; Wang, L.T.Item Selected Geomorphic Features of Delaware(Newark, DE: Delaware Geological Survey, University of Delaware, 2000) Ramsey, K.W.; Schenck, W.S.; Wang, L.T.The shaded relief image on the left was created using 30-meter resolution Digital Elevation Models (DEMs). The DEMs were developed by John Mackenzie, University of Delaware College of Agriculture and Natural Resources Spatial Analysis Laboratory, from rasterized 1992-93 United States Geological Survey (USGS) Digital Line Graph (DLG) hypsography data. He also combined these data with zero-elevation contours extracted from 1989 Landsat TM Band 7 satellite imagery for coastal quadrangles. The image was digitally enhanced using a false sun angle of 45 degrees shining from the northwest to exaggerate the geomorphic features. In reality the Delaware Coastal Plain is not "mountainous," as it looks in this enhanced image. The hydrology layer was created using USGS 30 x 60 minute and 7.5 minute series DLG data. Municipal boundaries were created using the Delaware Municipal Boundary Framework Layer. Both maps are projected in Universal Transverse Mercator, Zone 18 (UTM 18) on the North American Datum 1983 (NAD83).Item The Setters Formation In The Pleasant Hill Valley, Delaware: Metamorphism And Structure(Newark, DE: Delaware Geological Survey, University of Delaware, 1997) Plank, M.O.; Schenck, W.S.The Setters Formation, identified on the southeast side of Pleasant Hill valley in well Cb13-16, contains the prograde mineral assemblages (1) microcline, biotite, and sillimanite +/- garnet, and (2) microcline, biotite, sillimanite, and muscovite +/- garnet. These pelitic assemblages allow us to infer peak metamorphic conditions between 620° and 680°C and 4 to 6 kilobars pressure, if PH20/Pfluid is > 0.5. There is some evidence in the drill cuttings to indicate that partial melting accompanied the formation of sillimanite, thus constraining peak temperature to > 640°C.